Google's streaming technology, known as Google Cast, is built into quite a few different products these days, and to interact with those products and get things like the Chromecast set up, you would use the official Google Cast application that can be installed on your device. That in particular isn't changing, but Google is switching up the name as they're now rebranding the Google Cast app to Google Home, something which was discovered back in the beginning of October. As part of the changes Google isn't just giving the app an entirely new name, it's also changing up the icon for the app, naturally, and it's given the app a new coat of paint so the color scheme for the user interface is a little different than it used to be.
When it comes to changes with the app beyond the new color scheme, which is now a mostly complete white UI instead of a white backdrop and a Blue header. Google did keep the yellow line that denotes which tab you're on, although there are now only two tabs within the app instead of three, and the names of the tabs have changed as well, and are now "Watch" and "Discover" instead of the What's On, Devices, and Get Apps tabs.
There is also no longer a search bar up top as Google has moved that functionality into a Floating Action Button in the bottom right corner, and the functionality of the devices tab has been transplanted to the top right corner with a Devices button. The Hamburger Menu is still where you'll access which account to use with the app, and it also still holds access to things like the Account Preferences, Offers, and tips and tricks on how to cast. There is also a link for casting the screen of your connected device, and a link to the Google Store which opens up in your browser. For the most part, the app looks very much the same, and the layout is not too much different from before. The Watch page, which used to be What's On, still displays lists of cards for what you can watch and cast to the big screen, while also retaining a button link to open the displayed content in the app on your device. If you haven't received the update for the Google Cast app yet, you can grab the APK from the button below.